Where can you find parts and the value of a model SD594 semi-automatic Western Field .22 rifle?

You may want to double check the model number on your Western Field. I have one myself, and it is a model SD59A. I've been told that it was manufactured by Savage/Stevens, and that from that manufacturer it was built under the model number 6. This is a good place to start on your parts hunt. http://www.e-gunparts.com/ I paid $85 for mine at a pawn shop, and it's in pretty good shape. But some people may tell me I paid too much.